Green tea contains many active ingredients of benefit to humans. These active ingredients include catechins such as epicatechin, epigallocatechin, epicatechingallate and epigallocatechingallate, which are known for anti-tumor effect, anti-oxidizing effect, anti-bacterial effect, detoxication of heavy metals and suppression of high blood pressure.
Nowadays, studies are being actively conducted to search for pharmacological active substances in the green tea other than the catechins. Polyphenols extracted from the green tea are reported to have an inhibitory effect on photo-aging and can be used as a UV protecting agent. Also, gallocatechingallate as an isomer is studied for its extraction. Further, dermal formulations for external application comprising the green tea extract are studied for improvement of wrinkling and elasticity deterioration caused by skin aging. This is because the polyphenols contained in the green tea can eliminate free radicals and activate defense factors that are related to the anti-oxidation in the skin, and thereby, improve wrinkling and skin elasticity.
In addition, water soluble polysaccharides existing in the green tea are known to have immunization, anti-radioactivity, anti-coagulant, anti-tumor, anti-HIV and reduction of blood glucose level activities. The polysaccharides isolated and purified from the green tea have an activity to suppress the bonding between Propionibacterium acne and atopic Staphylococcus aureus and the bonding between Helicobacter pylori and host cells in the human body. In cited references, ion exchange and gel filtration chromatography are used to separate the polysaccharides of the green tea. However, the ion exchange and gel filtration chromatography processes are inferior in terms of economical efficiency since they require excessive time, and no techniques for mass production have yet been established.
Thus, the green tea extract cannot avoid the necessity of being used in combination with other effective ingredients, since it has poor formulation stability such as discoloration and cannot be used in a large amount to be capable of providing desired effects such as whitening, moisturizing and anti-wrinkle effects despite having various active substances.
Also, polyphenols which are representative ingredients of the green tea and known to have anti-oxidizing effect must be secondarily processed, for example, into a capsule form, since they have poor formulation stability and stability as they are. However, even when formulated into the capsule form, the polyphenols can be readily discolored over time and thus cannot be used as cosmetic materials.